1. Field of the Invention
The present invention relates to a tape scale, and in particular, to a jig and a method for applying a tape scale to an object.
2. Description of the Related Art
Optical encoders for detecting relative movement of two members are known. Referring to FIG. 1, an optical encoder 100 includes a detector 101, which is attached a member 105, and a tape scale 102, which is applied to another member 106. An absolute scale pattern, an incremental scale pattern, or both of these patterns is/are formed on the tape scale 102. The detector 101 emits light to the tape scale 102, receives light reflected by the tape scale 102, and outputs a detection signal on the basis of the reflected light.
Next, a method of applying a tape scale by using an existing tape scale application jig will be described. The tape scale is passed through the tape scale application jig, and the tape scale is applied to an object by sliding the application jig while peeling off a backing tape, which protects an adhesive layer on the back side of the tape scale (see, for example, Japanese Patent No. 2837483 (page 4 and FIGS. 5 to 8)). Before applying of the tape scale, it is necessary to extend the tape scale beyond both ends of the application jig (see, for example, Japanese Patent No. 2837483 (FIG. 6)).
Therefore, the existing tape scale application jig has a problem in that it is incapable of applying a tape scale that has a length smaller than the entire length of the application jig.
In a case of applying a tape scale without using an application jig, the following problems arise. First, the tape scale may become curved in a lateral direction or in a direction of a gap. Second, the tape scale may be applied to a position that is displaced from a desirable position. FIG. 2 illustrates an example in which a tape scale 103 has become curved in the lateral direction when the tape scale 103 was applied to a member 107. FIG. 3 illustrates an example in which a tape scale 104 has become curved in the direction of a gap when the tape scale 104 was applied to a member 108.